The present invention relates to an apparatus and method for processing signals. More particularly, the invention relates to an apparatus and method for processing signals, which can automatically detect or retrieve commercial messages added to TV-broadcast programs.
Generally, each of sponsored TV-broadcast programs consists of a program proper and sponsor's commercial messages inserted in the program proper. (Hereinafter, the commercial messages will be referred to as “CMs,” for the sake of brevity.)
Television viewers are interested mainly in the program proper. Most of them wish not to see the CMs inserted in the program proper.
On the other hand, some viewers may sometimes want to see CMs, particularly those which tell stories and those in which famous actors and/actresses make appearances.
A sponsored TV-broadcast program may be recorded on a recording medium such as a magnetic tape or a magnetic disc. If the program proper and CM constituting the recorded program can be independently reproduced from the recording medium, it will satisfy not only people who wish to enjoy seeing the program proper only, but also people who want to see the CM only.
As a technique of reproducing the TV program proper only, skipping the CM, is known. This technique, called “CM-skipping function (CM-skipping function in broad sense),” is incorporated many types of home-use video tape recorders.
Four types of CM-skipping functions (CM-skipping functions in broad sense) are available. They are: CM fast-forward function, CM cutting fiction, CM-skipping fiction based on the broadcast mode, and CM-skipping function not based on the broadcast mode. Of these four types, the CM fast-forward fiction is implemented by utilizing the fact that CMs are produced in Japan, usually in units of 15 seconds. While seeing the recorded TV program, the viewer may push one time the CM-skip button on the remote controller, fast running that 15-second CM part of the tape and thus skipping the CM. If he pushed the button twice, then CM part (30 seconds) of the tape is fed fast forward and thus skipped. This technique of fast feeding the tape forwards is disclosed in, for example, Jpn. Pat. Appln. Laid-Open Publication No. 10-269651. Further, Jpn. Pat. Appln. Laid-Open Publication No. 9-307841 discloses the technique of determining the end of fast feeding of tape upon detecting a black frame of the video signal and the no-sound part of the audio signal are both longer than a predetermined length, not upon lapse of the predetermined time as in the technique of fast feeding the tape forwards.
The CM cutting function is achieved by using the fact that CMs are broadcast often with stereophonic sound in Japan and a pilot signal is multiplexed on the TV-broadcast signal, indicating that the audio signal is in monaural mode, stereophonic mode or sound-multiplex mode. To record a TV-broadcast program proper with sound of, for example, the monaural mode or sound-multiplex mode, the recording is interrupted for any stereophonic part (CM-recorded part) of the tape. Thus, the CM-recorded part of the tape is, so to speak, cut. The technique of cutting the CM part is disclosed in, for example, Jpn. Pat. Appln. Laid-Open Publication No. 3-158086 and Jpn. Pat. Appln Laid-Open Publication No. 3-2622872.
Like the CM cutting function, the CM-skipping function based on the broadcast mode (CM-skipping function in narrow sense) is implemented since the CM is different from the program proper in terms of broadcast mode. In the CM cutting function, the CM is cut while the program is being recorded as described above. In the CM-skipping function based on the broadcast mode, the broadcast mode is recorded on the tape, as well as all images and sound, and any stereophonic part (CM-recorded part) of the tape is fed fast forward in the course of reproducing the entire program recorded on the tape. The technique of skipping a CM based on the broadcast mode is disclosed in, for example, Jpn. Pat. Appln. Laid-Open Publication No. 5-250762.
The CM-skipping fruition not based on the broadcast mode (CM-skipping function in narrow sense) is effected in accordance with the period in which a no-sound part exists in the audio signal, in which an image-changing part (where the image changes to another) exists in the video signal, or in which black level and white level appear in the broadcast signal. Any part of the tape, where the period is a multiple of 15 seconds is regarded as a CM-recorded part and is fed fast forward. The CM-skipping function not based on the broadcast mode is disclosed in, for example, Jpn. Pat. Appln. Laid-Open Publication No. 8-317342 and “A Study on the System for Detecting CMs in TV Broadcast Programs” (a technical report of Video Information Media Association, VIR97-22, 19/23, 1997).
The CM-skipping functions described above are performed by the TV viewers who operate home-use video tape recorders to record and playback TV-broadcast programs. The TV viewers need to determine whether this or that particular part of a program is a CM or not. The CM-skipping functions cannot automatically detect CM parts of the TV-broadcast program.
In the CM-skipping fiction based on the broadcast mode or the CM-skipping function (in the narrow sense), CMs are detected from the mode in which they are broadcast, e.g., the stereophonic mode. This function does not work in the case where the program proper is broadcast in the stereophonic mode. Nor does it work in the case where the CM is broadcast in the monaural mode or sound-multiplex mode. (Namely, the CM cannot be cut or skipped at all.)
In the CM-skipping function not based on the broadcast mode or the CM-skipping function (in the narrow sense), CMs can be detected without bothering the TV viewer or determining the broadcasting mode of the CMs. This function detects a CM by determining whether a period in which a no-sound part exists in the audio signal or an image-changing part (where the image changes to another) exists in the video signal coincides with a preset value or not. In the TV programs actually broadcast, however, the no-sound part may be shortened to adjust the time of the TV program or by switching operation. Hence, the no-sound part thus shortened may coincide with the preset value. In addition, the program proper may include a no-sound part or an image-changing part that coincides with the preset value. Thus, any CM having a no-sound part shorter than the preset value cannot be detected at all, and any no-sound part or any image-changing part in the program proper, which coincides with the preset value, may be detected as a CM.
A plurality of CMs may be broadcast continuously in a TV program. In this case , the four functions described above can detect the period in which the CMs are so broadcast, but cannot detect the period of each CM cannot. It is therefore impossible for the TV viewer to extract and enjoy any one of such CMs.
It is therefore desired that CMs be detected and retrieved with high reliability, from the TV broadcast signals.